Struct WindowShift

pub struct WindowShift { /* private fields */ }

window shift expression

Implementations

impl WindowShift

pub fn lag() -> Self

pub fn lead() -> Self

Trait Implementations

impl Debug for WindowShift

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl WindowUDFImpl for WindowShift

fn expressions( &self, expr_args: ExpressionArgs<'_>, ) -> Vec<Arc<dyn PhysicalExpr>>

Handles the case where NULL expression is passed as an argument to lead/lag. The type is refined depending on the default value argument.

For more details see: https://github.com/apache/datafusion/issues/12717

fn as_any(&self) -> &dyn Any

Returns this object as an Any trait object

fn name(&self) -> &str

Returns this function’s name

fn signature(&self) -> &Signature

Returns the function’s Signature for information about what input types are accepted and the function’s Volatility.

fn partition_evaluator( &self, partition_evaluator_args: PartitionEvaluatorArgs<'_>, ) -> Result<Box<dyn PartitionEvaluator>>

Invoke the function, returning the PartitionEvaluator instance

fn field(&self, field_args: WindowUDFFieldArgs<'_>) -> Result<Field>

The Field of the final result of evaluating this window function.

fn reverse_expr(&self) -> ReversedUDWF

Allows customizing the behavior of the user-defined window function when it is evaluated in reverse order.

fn documentation(&self) -> Option<&Documentation>

Returns the documentation for this Window UDF.

fn aliases(&self) -> &[String]

Returns any aliases (alternate names) for this function.

fn simplify( &self, ) -> Option<Box<dyn Fn(WindowFunction, &dyn SimplifyInfo) -> Result<Expr, DataFusionError>>>

Optionally apply per-UDWF simplification / rewrite rules.

fn equals(&self, other: &dyn WindowUDFImpl) -> bool

Return true if this window UDF is equal to the other.

fn hash_value(&self) -> u64

Returns a hash value for this window UDF.

fn sort_options(&self) -> Option<SortOptions>

Allows the window UDF to define a custom result ordering.

fn coerce_types( &self, _arg_types: &[DataType], ) -> Result<Vec<DataType>, DataFusionError>

Coerce arguments of a function call to types that the function can evaluate.